Question

A. Acid-Base Indicators
HMV (aq) <—-> H+ (aq) + MV- (aq)

yellow               violet

1. Explain, by considering how changes in [H+ ] will cause Reaction 4 to shift right and left, why the reagents (HCl and NaOH) in Steps 2 and 3 of the procedure caused the solution to change color.

Answer 1

The reaction HMVG, violet equilibrium reaction. According to Le-cha Hat Mu (aq) is an yellow ording to ople chatelier's princip increase in concentration of reactant will shift equilibrium the to right. & increasing the conc. of product will shift the equilibrium to the left a) Addition of Hol It will increase the [ht] (which is a product and to regain the equilibrium, the added it will react with more mi and the equilibrium will shift to left and the colour changes to yellow b) Addition of NaOH. It will increase the conc. of on and the added ot reacts with 4t AS a result the conc. of Ht decreases and hence equilibrium shifts to right. Colour changes to violet Note Le-chatelier's principle states that if a stress is given to a system at equilibrium the system will try to undo the effect of that change. Here the disturbance issor stress is the change in conc. of 4t